[Widespread idiopathic comedones and lichen ruber planus: clinical and histological association].

The presence of numerous acquired comedones on the trunk and limbs of an adult patient, with no other family member affected and with no triggering factors to explain their presence, requires us to rule out those conditions in which comedones are the predominant clinical feature. The fact that these lesions appear in association with areas of lichen ruber planus presents the dilemma of whether the lesions develop simultaneously by chance or whether there could be some pathogenic relationship. In the case we present below, we observed that, from a clinical point of view, the 2 types of lesion (comedones and lichen) were frequently closely related, with the comedones presenting a lichenoid halo, but they were sometimes separate. However, in all samples analyzed, histological study showed lichenoid infiltration of the comedones. A 72-year-old woman came to our outpatient clinic for mildly pruritic lesions that had been present on the trunk and limbs for approximately 2 years. The patient had a history of hypertension and dislipidemia, for which she had been on treatment with felodipine and pravastatin for at least 7 years. There was no family history of similar skin lesions. On physical examination, we observed small, shiny, erythematous-violaceous plaques and papules with a smooth surface, suggestive of lichen ruber planus (Figure 1). In addition, numerous comedones were identified on the trunk, arms, and thighs; some of these had an erythematous halo of lichenoid inflammatory appearance (Figure 2). A whitish, reticulated pattern was observed on the mucosa of both cheeks. There were no alterations of the hair or nails. The patient was unable to say whether the 2 types of lesion appeared simultaneously or in succession, and there was no history of the use of comedogenic products. We performed biopsies of the comedones, with the interesting finding of a lichenoid pattern around the infundibular microcysts of the comedones (Figure 3); this infiltrate was observed irrespective of whether there was a visible erythematous halo around the comedone or not. The biopsy from the violaceous plaques showed a linear lymphoid infiltrate in the superficial dermis and the presence of necrotic keratinocytes, also confirming the clinical impression of lichenoid lesions. There were no relevant pathological findings in the routine laboratory tests and serological tests for viral hepatitis were negative. The patient was treated with oral isotretinoin (0.5 mg/kg) for 4 months, with resolution of the lichenoid lesions and a marked reduction in the number of comedones. The presence of numerous comedones with a generalized distribution on the trunk and limbs, appearing in adult life, with no triggering factors and no family history of similar lesions is very rare. Recently, Zhang and Zhu1 reported a similar case in a boy who, like our patient, presented disseminated idiopathic comedones. The histological